The photograph of Dr. Lawrence's wife is a photograph of Peter Cushing's own wife. She died suddenly in 1971 and Cushing mourned for the twenty years he survived her, often commenting that his only real joy in life was contemplating being reunited with her after death.
According to Veronica Carlson, director Freddie Francis made Peter Cushing do multiple takes during the scene where he talks about his love for his wife. This caused Cushing great distress, and reduced him, and some of the crew, to tears.
Veronica Carlson didn't make another movie for almost 20 years after this film. She said in a 2011 interview that she reluctantly quit acting because every role she was offered required nudity, including the Hammer films, and she didn't want to take her clothes off anymore. She knew other actresses were taking them because they had no choice if they wanted to keep acting. But Carlson said she wanted nothing to do with it.
In the U.S., this movie was released as "Night of the Ghoul" and "The Thing in the Attic". Contrary to belief in some areas, this movie is not in the public domain: the rights holder is still Tyburn Film Productions.
Peter Cushing and Don Henderson played scenes together in Star Wars , A New Hope.